Lecture 2- Natural Selection Flashcards
What are the two competing theories on origin of species?
Special creation & descent with modification
What does the law of succession state?
Refers to how fossils of the same species from the same geographical area. So fossil succession can be found miles away in adjacent rock.
What is meant by a transitional form?
Fossils that exhibit traits common to ancestral groups and descendant groups.
What is meant by vestigial structure?
Often homologous to structures that are functioning normally in other species- structures that may seem to have no purpose- appendix
What does homology refer to?
Similarity due to common ancestry.
What is meant by structural homology?
Organs and bones that appear in different animals underlying anatomical commonalities demonstrating descent from common ancestor- different functions from common ancestry.
What is meant by structurally analogous?
Structures in different species having the same function but different structure- no common ancestor.
What is meant by developmental homology and who studied it?
Richardson et al. (1998) embryos from different vertebrae show striking similarities in early development.
All have pharyngeal pouches and tails- chicken human bat snake
Why study developmental homology?
Studying embrylogical development of living things provides clues to the evolution of present day organisms.
What does molecular homology refer to?
All organisms on earth are composed of dna. Holds info to an organisms ancestry. All living things fundamentally alike.
What are the assumptions of evolutionary theory?
- There is variation in individuals.
- This variation is heritable.
- Variation productive differential reproductive success.
- Traits suited for reproductive success will eventually dominate.
Why are Darwin’s finches significant?
He found that different variation of finches came from one species in South America. All had distinct variations from food sources and environment. Breeding is unlikely so must have evolved- supporting variation.
LED TO THE THEORY OF NATURAL SELECTION.
What does speciation refer to?
Species= set of animals or plants in which the members have similar characteristics and can breed with each other. Reproductive isolation leads to speciation- selection and mutation occur in new groups.
What are factors effecting hominid evolution?
Bipedalism-3.6mya, narrowed birth canal and efficient movement.
Diet- cooked is easier to digest, divert energy to brain growth.
Brain- increases brain size
